Inspiroation: A novel synthesis of spirocycles based on a palladium‐catalyzed intramolecular ipso‐Friedel–Crafts alkylation of phenols (see scheme; dba=dibenzylideneacetone) and indoles is described. Mechanistic studies show that the reaction proceeds through an unprecedented rearomatization‐assisted oxidative addition.
AbstractWe have developed a novel synthetic method to furnish spiro[4.5]cyclohexadienones using an gold‐catalyzed carbocyclization of phenols with a terminal alkyne via an intramolecular ipso‐Friedel–Crafts alkenylation. Using 2–5 mol% of gold catalyst, 1 equiv. of methanesulfonic acid, and 1 equiv. of 2,6‐di‐tert‐butylpyridine, a variety of spiro[4.5]cyclohexadienone derivatives with an exo‐cyclic olefin unit was obtained in good to excellent yields. The divergent synthesis of dihydronaphthalene derivatives was also examined based on the newly developed gold catalysis.magnified image